New York s JFK airport began strict new health screenings for travelers from Ebola-hit West African nations as countries across the world scrambled Sunday to stem a deadly Ebola outbreak.

Passengers and crew arriving at John F Kennedy International Airport from the three countries at the centre of the outbreak will have their temperatures taken and be screened for signs of illness and answer questions about possible exposure, the US Centers for Disease Control and Prevention (CDC) said.

Exit screening might not find every person with Ebola, however, it does not have to be perfect to help reduce the spread of Ebola, the CDC said in a statement.

Four other major US airports are to start similar checks next week.

In Latin America, Peru and Uruguay have announced airport measures and Mexico and Nicaragua planned to tighten controls of migrants heading for US soil as an Ebola precaution.

And in Madrid, the serious condition of a Spanish nurse, who was the first person to become infected with Ebola outside of Africa, showed signs of improving.

More than 4,000 people have died from Ebola in seven countries since the start of the year, according to the UN s World Health Organisation, and the disease appears to be outpacing efforts to fight it.

The virus is far ahead of us and every day the situation gets worse, the head of the United Nations emergency Ebola mission Anthony Banbury, told UN leaders after a tour of Liberia, Guinea and Sierra Leone, the nations worst affected by the epidemic.

Amid fears of a global contagion, two countries on Saturday ruled out suspect cases.

And in Macedonia, tests showed that a British man who died displaying Ebola-like symptoms did not have the virus, officials said.

- Spanish nurse s condition improves -

IMF chief Christine Lagarde on Saturday pleaded with people to remember that all of Africa has not been hit with the deadly Ebola epidemic, which remains relatively isolated in three countries.

With those three West African nations -- Sierra Leone, Guinea and Liberia -- already seeing their economies crumble because of the disease, Lagarde emphasised: We should be very careful not to terrify the planet in respect of the whole of Africa.

In Spain, attention remained focused on 44-year-old nurse Teresa Romero, whose condition improved in the night. She is conscious and talks from time to time when she is in a good mood, a hospital source told AFP.

Romero s brother confirmed late Saturday that his sister was improving.

She no longer has a fever, it appears that while remaining seriously ill

she s getting better and moving forward, She still in a serious but stable condition and this gives us hope, Jose-Ramon Romero told private television channel La Sexta.

Teresa Romero is thought to have contracted the disease in late September in a Madrid hospital while caring for a Spanish missionary infected with Ebola in Africa who later died.

Fifteen other people, mostly hospital staff as well as Romero s husband, are under observation at the Carlos III hospital where Romero is being treated. The hospital said none of them were showing any symptoms.

Officials at the Madrid hospital insisted there was no risk of infection from patients under observation, including Romero s husband, who were photographed leaning out of the windows of their hospital rooms.

The Spanish hospital source added that doctors started treating Romero with the experimental Ebola treatment ZMapp late on Friday.

- Experimental drugs, vaccine -

There is still no vaccine or widely available treatment for Ebola, but ZMapp, made in California, is one of several drugs that have been fast-tracked for development.

And Russia s Health Minister Veronika Skvortsova announced Saturday that her country has created three (Ebola) vaccines... and we think they will be ready in the next six months .

Trials for an Ebola vaccine are under way in Mali, which has no cases of the disease but borders Guinea where the outbreak began.

That vaccine is being developed by the British drug company GlaxoSmithKline and the US National Institutes of Health (NIH).

The WHO reported 4,033 people have died from Ebola as of October 8 out of a total of 8,399 registered cases in seven countries.

The sharp rise in deaths came as the UN said aid pledges to fight the epidemic have fallen well short of the billion (800 million euros) needed.

Britain held a nationwide exercise on Saturday to test its preparedness for an Ebola outbreak.

Health Secretary Jeremy Hunt said afterwards that the country was ready to cope with any outbreak.

The Canadian government advised its citizens to leave the west African countries most affected by Ebola. It took measures at its own borders to screen for potentially exposed travellers.

Ebola concern also spread to the sports world, with hosts Morocco calling for the January-February 2015 Africa Cup of Nations to be postponed, but the African Football Confederation said the schedule would not be changed.